Transparent tissue and process of making same



Patented Feb. 4, 1.936

' TRANSPARENT TISSUE AND PROCESS OF MAKING SAllIE Carleton Ellis,Montclair, N. J., assignor to Ellis- Foster Company, a corporation ofNew Jersey No Drawing.

Application November 14, 1929,

Serial No. 407,292. Renewed May 31, 1934 4 Claims.

This invention relates to paper of a transparent to translucentcharacter containing a synthetic resin augmenting transparency whichsynthetic resin is preferably resistant to light in the sense that itdoes not discolor and turn brown on relatively long exposure to daylightor sunlight; such synthetic resin preferably having incorporated with itaplasticizing agent of adequate light stability: the resulting sheetmaterial, in view of being relatively light-fast or light-stable, havingutility as a wrapping paper which permits of a display of the contentsof the package wrapped therewith.-

The process of the present invention is based on the treatment of-paper,preferably a thin and rather-tough paper such. as tissue, parchment,rice paper, crepe paper and a calendered paper known as glassine,commercially used in the manufacture of envelopes displaying the addressthrough an aperture on the face thereof.

The laminated material may take the form of plain pressboard or by usingalternating layers of difierent colors a thick sheet or block may bebuilt up which if desired may be cut into various shapes, the cut edgesof which will show alternating colors. 1

In making the laminated material it is possible also to insertphotographs or pictures which,

provided the pressing is carefully done, may be w'e'mbedded in the sheetand thus protected.

In other cases metal flakes or powder such as gold flakes or aluminumpowder may be scattered through the laminations. Again strips of thetreated paper may be wound on 'a. mandrel N to form acylinder, coneandthe like and the mass subsequently pressed in the manner to bedescribed. I

A particular feature or the present invention is the production ofsheets which even though of considerable thickness will transmit light.Thin'laye'rs are practically transparent and the thicker layers are ofan opaqueness ranging from that of frosted or ground glass to a higherde-' effect is obtained by mixing the shreddings of different colors andhot pressing.

Furthermore it is possible to take portions of 65 the shreddings andplace in different parts of the mold so that the colors in a givensheet, I

block. or molded piece will be segregated.

In carrying out the molding or hot pressing of such material theshreddings may first be tableted if desired and then molded at therequisite temperature. The molds may have surfaces which give anembossed effect or print in raised or depressed letters any desired'name or emblem. In some cases fillers may be incorporated with thepaper sheets.

From this material I propose to make such articles as brush handles,combs, beads and other. articles of personal adornment; handles forvarious equipment, boxes, jewel cases, ash trays,

lamp shades, wall board, table tops, photograph frames, pen and pencilholders, game counters, buttons, advertising devices and the like.

As a material for coating or impregnating the paper I prefer to use ureaformaldehyde resin or a mixture of this resin with acetone formaldehyderesin. ,'Other compositions such as. urea phenol formaldehyde resin andmixtures of urea resin with glycerlde resins also may be employed insome cases. Some of the glycerlde resins, for example the tartrate andlactate are soluble or emulsifiable with water and can be readilyincorporated with urea formaldehyde syrupy material described herein andas set forth in my copending applications.

The urea resin material has a very desirable binding effect on the papersheets and lends a degree of translucency or transparency which ishighly desirable for such articles as are particularly contemplatedunder the present invention.

The following are illustrations of compositions which may be employed.

(A) Urea formaldehyde syrup: 30 parts by weight of urea are dissolved in120 parts by weight of aqueous 40' per cent formaldehyde solution. 3parts of powdered phthalic anhydride are added and the mixture is verygradually heated under a reflux condenser until clear. It is advisableto avoid any vigorous boiling'when a colorless trans-'- parent syrup isdesired. The solution so' obtained usually has a content of from to 60per cent total solids. I I

(B) Acetone resin solution. 6 parts by weight of acetone are mixed with45 parts of aqueous 40 per cent formaldehyde and 6 parts of a per centaqueous solution of caustic soda are added. The mixture is allowed toreact which occurs quickly with the evolution of heat. A slightly yellowhoney-like product separates. As soon as the contents of the reactionvessel become milky cold water is added to check the reaction. Thehoneylike material is washed to remove alkali and is dissolved inalcohol, preferably employing a 30 per cent solution.

The paper may be impregnated with the urea syrup (A) or with the acetonehoney (B), or preferably with a mixture of (A) and (B). For example whenmixed in equal proportions the solution will contain about 2 parts ofthe lrea solid to one part of the acetone solid. A pro ortion whichgives about 1 part or slightly more of the acetone honey to about 3parts of the urea syrup molds readily without troublesome blistering andwith the smooth surface finish which is desirable.

The impregnation of the paper may be carried out by immersing it orpassing it through a bath of the foregoing and allowing the sheets todrain and dry in the open air; or the paper may be passed continuouslyfrom a roll through the bath and then through a set of squeeze rolls toremove excess of the liquid and finally passed through a drying chamberto remove the solvents. In some casesvthe impregnation may be carriedout by the vacuum and pressure process. This is desirable when the paperused is of greater thickness as it is desirable to impregnate to fillthe canals of the fibers in order to secure the highest degree oftransparency or translucency.

Sheets of such impregnated paper are placed in a hot press superposed toform a pack of say 20 to 100 sheets and are pressed at a temperature of120-130 C. for minutes at 3000 pounds pressure. Preferably the mold iskept in a cold pres for 2 or 3 minutes before opening. If stickingoccurs the surface of the mold may be treated with a lubricant such asstearic acid. In some cases the mold may ,be advantageously dusted withfine powder of aluminum palmitate, zinc stearate and the like.

If the paper is over-dried the sheets do not stick readily and inaddition to poor adhesion there is a lack of flow which prevents anyirregularities of the mold affording their desired impression. Inlaboratory experiments it has been found sufllcient to allow the paperto dry in the open air at room temperature and then in an oven at 60-70C. for minutes.

Sheets of laminated material made in this manner in addition to theirattractive translucent qualities exhibit remarkable strength and adesirable degree of elasticity.

Sheet of paper which have been colored in various colors which harmonizemay be shredded or cut and the clippings or shreddings mixed, placed inthe not press or first in a tablet press if desired and submitted tomolding at a temperature of about 120-130" C. Higher tempera- .tures areliable to cause blistering or a yellowing demarcation.

On the other hand by placing differently c01- ored irregular cut piecesof paper in the mold, for example paper out in various geometricaldesigns and pressing articles are obtained having peculiar and strikingappearance.

It is also possible to prepare an imitation of tortoise shell. Forexample in one case the folturbid.

lowing procedure was employed using paper impregnated as describedabove:

Sheets of white paper were placed in the mold followed by sheets ofpaper colored a light yellow, then clippings of a reddish brown colorwere scattered in the mold, followed by layers of yellow paper and thenof white paper. The procedure employed in one case was to place a fewscraps of reddish brown paper in the mold, then 2 sheets of white paper,1 sheet of yellow paper, then an additional quantity of the red or brownclippings, followed by 6 sheets of white paper, then more red clippings,one sheet of yellow paper, more red clippings, 5 or 6 sheets of whitepaper, red clippings, 'white paper, red clippings and so on until a massof the suflicient thickness was obtained.

Also it is possible to employ other resins for example a composite resinin which urea is used in making. Thus 60 parts by weight of urea, 60parts of phenol and 240 parts of aqueous. 40 per cent formaldehydetogether with 10 parts of powdered phthalic anhydride were slowly heatedin an open vessel until a clear syrup resulted. About 10 per cent ofalcohol was added before cooling in order to keep the syrup frombecoming In another case 75 parts of urea, 25 parts of phenol and 325parts of the formaldehyde solution together with 10 parts of phthalicanhydride were heated in like manner. The solution usually containsabout 45 to 50 per cent of total solids and may be used in this form forimpregnation purposes. It is better adapted for molding at highertemperatures than the urea resin alone or the urea acetone resin.

The treatment of tissue paper and especially a product of the characterof giassine paper with the urea resin or urea acetone resin greatlyincreases its transparency and such material may be used in place ofparchment paper for example in the manufacture of apertured envelopesand the like.

It is possible also to add to such impregnating compositions as havebeen described various substances to modify the flow or appearance ofthe product, including such additions as glue and casein or materialssuch as linters or flock. Heavy pressboard may be obtained by usingblotting paper.

An advantage in using aqueous material such as urea syrup or the syrupwith an alcohol solution of acetone resin, etc., is that paper,especially a highly calendered translucent paper of the type ofgiassine, impregnates very readily, whereas when the effort is made toimpregnate such paper with alcoholic solutions of say shellac or some ofthe natural resins difficulties arise in molding and a product of poorappearance and imperfectly stuck together results. In the case of theurea resin mixtures there may be some change in the fibers or someeffect which gives a product that is so well cemented together thatsplittings along the lines of the lamination is difficult. The productmore nearly resembles horn or bone, ivory in its texture other thancolor. Frequently a sheet when broken will show almost a conchoidalfracture. In any event there is not the tendency to cleavage along thelaminae and the fracture is usually irregular. The surface is very hard.

In this way a tough, transparent, translucent material in natural coloror artificially colored, or multi-colored maybe obtained which isproposed for use for many purposes to replace glass, celluloid and thelike. It has the advantage of bel amasas' new burning and 'very ofignition.

This property may be enhanced by including flre-' proofing salts. Theresistance to water (or waterproof quality) is improved by baking themolded articles or pressed sheets at a-mild heat for example 60-70" C.for half an hour or longer depending on the thickness of the pressedproduct. The present invention includes pressed and baked material ofthis character andjthe process of making same.

The foregoing is derived largely from Serial 742,719, relatingparticularly to plasticized products preferably of a transparent totranslucent character. containing essentially plastics of the ,ureaaldehyde type. In Serial 185,660, which is a continuationof thedisclosures of Serial 689,165,

and other copending applications, I have referred to variousplasticizing bodies such as glycerol,

' glycol and similar plasticizers or modifying agents.

Such plasticizers may be used in addition to the plasticized resinsreferred to herein, it being an.

object in the preferred form of the invention to produce a transparentor semitransparent thin discolor and'altervisibly tothe detriment of.the

requirements of a transparent or semi-transparent wrapping paper, andthe like.

Attention is also called to Serial Number 742,- -'ll9 and Number 28,505in connection with and supplemental to the foregoing description,

Reference is made herein to companion application, Serial No. 689,165,flied January 28, 1924.

The methods of making the urea formaldehyde resins and related resinsand the resins per se obtained by such methods are claimed inapplication. Serial No. 689,165. Reference is also made above tocompanion application, Serial No. 28,505, filed May 6, 1925, which is adivision of application, Serial No. 689,165. Methods of making the ureaformaldehyde type resins in which the reacting ingredients are firstreacted in an alkalin medium, followed by acidification, and theproducts resulting from such methods are claimed in applicationjSerialNo; 28,505. Reference is made above to companion application, Serial No.742.- 719, filed October 9, 1924. The methods of making laminatedpressboard from sheets of thin paper bound together by a bindercomprising the urea type resins and the use of. papers of differentcolors in such-methods, are claimed in application 742,719. Referencehas also been made above to companion application 185,660, filed April21, 1927, entitled Laminated vitriform sheets, etc., in whichapplication there is claimed laminated products obtained by cementingtogether sheets of material by binding agents ineluding resins of theurea formaldehyde typ and particularly sheets of glass thus boundtogether.

What I claim is: 1. Paper carrying a transparency augmenting resinincluding a urea aldehyde resin and a plasticizing synthetic resinincluding an acetone formaldehyde resin. I

2. Paper carrying a transparency augmenting resin including a ureaaldehyde resin and a plas-H ticizing synthetic resin including a phenolformaldehyde resin.

3. Glassine paper carrying a urea aldehyde resin.

4. Glassine paper impregnated with urea aldehyde resin and acetoneformaldehyde resin.

CARLETON ELLIS.

